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Pin of
Octal
Plug
Connected
to
6
~
7
1
2
4
or
5*
3
*
[f
the
preamplifier requires
350
VDC,
use pin
4;
If
the
preamplifier requires
less
than
350
VDC,
use pin 5
and
connect
a
dropping
resistor
of
appropriate value and vol-
tage
rating
from
pin
4
to
pin
5
of the octal
socket an
the
HF-35chassis.
Far
example,
if
the
preamplifier
In
ques-
tion requires
300
VDC
B+voltageat
IQma
drain, the
drop-
ping
resistor will
be required
to
drop
the
voltage
by 50
volts
(350-300
—
50)
at
a current
of
IGma*
By
Ohm's
Law,
the
required
resistance
in
ohms
Is
the
voltage drop
in
volts
divided
by
the current
in
amperes
or
50volts/*
01
amp. -
5000
ohms.
The
power
dissipated
in
the
resistor
In
watts
is
equal
to
the
voltage drop
In
volts
multiplied
by
the cur-
rent
in
amperes
or
50
volts
X
,01
amp
=
0,
5
watts-
For
safety a
resistor
of
double
the
wattage
rating
should be
used*
Therefore, a
5000
ohm
1
watt
resistor
is
required*
Preamp.
Power Lead
AC ON-OFF
AC ON-OFF
filament
(6*
3
VAC
1
fi
lament
(6*
3
VAC)
B+
ground
maintenance
.
CONTROL ADJUSTMENTS
The
INPUT
LEVEL ADJ.
control
is
Intended
to
protect the
speaker system from
"blasting
11
should
someone
turn the
preamplifier-control unit
level controls to
full,
by per-
mitting
you
to
attenuate
the
preamplifier output
signal
by
any
desired
amount
at the
input
to
the
power
amplifier
where
it
can
not
be
''fiddled
11
with.
Start
by
setting the
INPUT LEVEL maximum
comter-clockwise
(maximum
at-
tenuation), using
a
screwdriver.
Set the
LOUDNESS
con-
trol
on
your preamplifier
to
the
maximum
clockwise
posi-
tion
and
the
LEVEL
control at the
midpoint
of
its
range of
rotation*
Turn your
phonograph on and
play
on average
orchestral record*
Then
slowly
rotate the
INPUT
LEVEL
ADJ.
control
clockwise
until
the
music
Is
at
normal
(or
concert)
listening level*
This
completes
the adjustment,
which need
not
be repeated.
TROUBLE-SHOOTING PROCEDURES
Your
amplifier should require
little
service
except
for
nor-
mal tube replacement*
We
recommend
no
substitutions
for
the tube types
used
In this
amplifier.
The
EF86, EL34,
and
GZ34
types are distributed nationally
by
fheAmperex
Electronic
Corporation {230
DuffyAve*,
Hicksvi
I
le,
L*
I.
,
N.Y.) and
Mu
Hard
Ltd.
(Interna
tional
Electronics
Corp*,
Q] Spring
St.,
N.Y.
12,
N.Y*)
If
necessary,
replace-
ments can be obtained
directly from
EICO.
It
should
be noted
that
slight
red coloring
of the
EL
34
out-
put tube plates
In
operation
is
not
abnormal and
does not
Indicate
that
the
amplifier
is
operating improperly*
The
HF-35
is
intended
for
operation
at
a
line
voltage
of
117
volt
AC,
Component
failure
Is
likely
at
a
line
vol-
tage
above
124
volts
AC,
If
the
line
voltage
at
your
location
is
higher than 120
volts,
use the special tap
that
is
provided
on
the
power
transformer.
Disconnect
the
black-red wire from
the fusehotder.
In
its
place,
connect
the
black-green wire
to
the fuseholder*
Tape up
the
black-
red
wire
to
prevent
It
from
shorting-
This
provides safe
operation
up
to
line
voltage
of
132
volts-
If
your
line
voltage
is
above
this,
use a voltage adjusting
device
or
vol-
tage regulator of
adequate volt-ampere
capacity (200VA).
To
facilitate servicing,
remedial
and
trouble-shooting pro-
cedures
have been provided
in
the
TROUBLE
SHOOTING
CHART
that follows.
A VOLTAGE
AND
RESISTANCE
CHART
is
also
provided
as
an
aid
in
locating defective
components and
to
permit a
careful,
stage-by-stage
check
of the amplifier.
DC
operating voltages
are
given both
at
no
signal
and
at
a
signal
developing 35watts output
as
well
as
the
corresponding
Ike
signal voltages.
To
isolate
the source of unusual
hum
or noise
In
your
system,
first
turn off
the
AC
power and
then
unplug
the
audio
cable connecting
to
the amplifier
input.
Then
turn
the
AC
power on
again
and
note
whether
humor
noise has
decreased.
If
It
has,
the fault
is
in
the
preampi
ifier
or
associated
equipment and
measures should be taken
to
cor-
rect
It
as
described
In
the service notes
for
these
units.
|f
It
Is
desiredto provide a
good
building
ground
For
your
entire system, run a lead
from under speaker connection
terminal
"G"
to
a cold
water
pipe*
Do
not
connect
such
q
ground wire
to
other
components
in
the system.
If
the trouble
is
no output
or
low
output
and
the amplifier
is
suspected,
check
AC
signal
voltages
starting at
the in-
put
and working
step-by-step toward the output,
using a
sine
-wave
audio
signal
generator
and
a
VTVM,
Turn the
INPUT
LEVEL ADJ.
control
maximum
clockwise
(no atten-
uation)
and
set
the Input
signal
to
0*43
.alts,
ihe cor-
responding
grid
and
plate signal voltages
for
this
Input
are
indicated
on
the
schematic diagram.
This
procedure should
suffice
to
localize the defective stage.
If
the trouble
is
an
excessively
distorted output,
try
tube
replacement,
signal
tracing
or
procede
directly
to
voltage
and
resistance
measurements.
When
the defective stage
is
localized,
procede
to
a re-
sistance
and
voltage
check
of the stage,
using the data
in
the Resistance
and Voltage
chart.
Disconnect
the
ampli-
fier
from
the
power
line
and
discharge capacitors
prior
to
making any
resistance
check and
prior
to
removing
either
or
both
of
the
EL34
output
tubes*
5
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Table of Contents
Troubleshooting
